As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
After take off and selecting bleeds on, the FO and FA reported smelling an odor followed by the lavatory smoke detector sounding. Selected bleeds off, the odor went away and the smoke detector extinguished. Inspected aircraft bleed system, ran aircraft for 15 minutes with bleeds on. Ran duct temp up above 65 degrees for 15 minutes. No odor noticed or smoke detector went off. Suspect oil in bleed ducts due to previous work on APU.